There's a bizarre cast of characters behind those power wheelchair ads, including 'brainwashed' patients and coerced doctors. It all adds up to Medicare fraud.

“Life was passing me by. I wanted to do more, be more independent. Now I’m enjoying life more, and it feels great. I have The Scooter Store to thank for that,” says the television-ad voiceover accompanying a senior woman who is shown “enjoying life more” as she scooters around her kitchen, making cookies with a young girl.

Bait like baking and granddaughters is just one of the ways companies that market power wheelchairs and mobility scooters are seducing seniors with the promise of freedom and independence. Add in birthday parties, baseball games, and plenty of high-fiving, laughter-filled moments with grandkids — all possible because of newfound mobility via power chair, or so say the commercials – and you have a $1 billion market in the U.S. for the motorized wheels.

But the two largest scooter companies in the country, The Scooter Store and Hoveround, who together spent more than $180 million on advertising in 2011, are also at the heart of a growing controversy. Detractors say the ads create the misleading impression that the devices are a convenience rather than a medical necessity. They claim that the scooter commercials appeal to senior emotions, and cause patients to pressure doctors to prescribe unnecessary equipment.

Medicare is only obligated to foot the bill when seniors are unable to use a cane, walker or regular wheelchair. Government inspectors note that some 80 percent of the scooters and power wheelchairs paid for by Medicare go to people who don't meet the requirements. Members of Congress say the TV spots lead to hundreds of millions of dollars in unnecessary spending through Medicare.

"Patients have been brainwashed by The Scooter Store," Dr. Barbara Messinger-Rapport, director of geriatric medicine at the Cleveland Clinic, told NBC News. "What they're implying is that you can use these scooters to leave the house, to socialize, to get to bingo."

And more than just Medicare dollars are at risk: Doctors note that seniors who use scooters for convenience rather than necessity can become sedentary, leading to obesity and further health problems.

It’s hard to blame the patients; advertising can be strong and insidious – and who wouldn’t want to have the convenience of increased mobility if their walking ability had been compromised? And indeed, for those unable to get around without some added power, what a game changer it must be.

Insurance executives say doctors who don't understand the Medicare requirement are responsible for the mess as well. Beyond just not understanding the role of power wheelchairs and scooters — and the federal guidelines regulating them — doctors say the scooter companies are just as bold with health professionals as they are with the elderly. Company reps sometimes accompany seniors to their doctor appointments to "clinch the deal."

In February, nearly 150 agents from the FBI, the Department of Justice and the Texas attorney general's Medicare fraud unit raided The Scooter Store’s headquarters, causing no end of problems for the company and leading to substantial layoffs. Federal authorities declined to comment about the raid, but industry critics in Congress applauded the action.

"This raid is a welcome step toward cracking down on waste and fraud in Medicare," said Sen. Richard Blumenthal, D-Conn. and a member of the Senate Aging Committee. "I have urged action to stop abusive overpayments for such devices — costing taxpayers hundreds of millions of dollars and preying on seniors with deceptive sales pitches."